Limited external beam and interstitial 192iridium irradiation in the treatment of carcinoma of the base of the tongue: a ten year experience.

A total of 70 patients with histologically proven diagnosis of carcinoma of the base of the tongue were treated with primary irradiation between May 1974 through April 1984. Fifty-eight (83%) of these patients had locally advanced tumors (Stage T3, T4, N2, N3). Fifty-one of the 70 (73%) patients had clinically palpable neck nodes at first presentation. All patients received a combination of external and interstitial irradiation. The dose of external irradiation was limited to 45-50 Gy over 4 1/2-5 1/2 weeks. Interstitial volume implants were performed 2-3 weeks after completion of external irradiation. The primary site as well as the vallecula, epsilateral pharyngeal wall, glossopalatine sulcus, tonsillar bed, and pillars were routinely implanted to encompass contiguous spread of the disease. The doses of implant varied according to the stage of disease, that is, 2000-2500 cGy for T1 and T2 lesions, 3000-4000 cGy for T3 and T4 lesions, with typical dose rates of 50-60 cGy per hour. The neck nodes were also separately implanted to deliver additional doses of 2000-4000 cGy in 50-80 hours. Overall, local tumor control was observed in 58 of 70 (83%) patients at minimum follow-up of 2 years. An absolute 3-year disease-free survival of the entire group was 67.0%. Treatment related complications such as soft tissue necrosis and/or osteoradionecrosis occurred in 8 of the 70 (11.4%) patients. The salvage of neck failures and the local failures was feasible in 74% and 46% of the patients, respectively either by surgery or by re-irradiation using interstitial 192iridium implant alone. This treatment region is well tolerated and it preserves the functional and asthetic integrity in most patients.